Control circuit for radio receivers



Feb. 13, 194o. 1 Q. T. LAUBE CONTROL CIRCUIT FOR RADIO RECEIVERS Filed Aug. 27. i938 .P J' Y :CF: i333 B0 Switchboard fig. 4

.227 other receiver control ckts.

Yb. other reci"l Cof/wl'oL chas.

INVENTOR Z'Laube' BY z f2! ATTORNEY Patented Feb. 13, 1940 unirse sTATEs rA'rsNr orrics CONTRL CIRCUIT FR RADIOLRECEIVERS Utto Theodore Laube, East Orange, N U J., as-v signor to'AmericanTelcphone and Telegraph i A Company, a` corporation of'NeW' York Application August 27, 19,38, `Serial No. 227,201

' v claims. (ci. r5o-42o) e other `transmitters and Sto ,select the receiver `de- This invention relates to signaling systems. More particularly, this inventionrelates to signaling systems employing means for selectively receivingsignals impressed upon two or more receiving devices.

In radio signaling l systems .suitablefor use at coastal harbor` stations, for example, it appears desirable to provide two or more radio receivers "located at various points so that low power ship transmitters in the service area may always be within reliable signal range of some one of the various receivers. In setting up. such `an arrangement the output circuits of the `various receivers may bewired to a commonterminal in such a Way that asignal receivedlby any one of the various receivers will be heard by the operator;

Inan arrangement of the type justlreferred to it has been foundthaty the signal-toenoise ratio at the commonv terminal to which the various receiver circuits are wired` will be determined 'largelyby the poorest of thesignals of any individual radio receiver. Thus, if but one of the various receivers has a low signal-to-noise ratio, the signals at the ,common terminalmay become practically unintelligible' and thev opera tor will be `unable to decipher the' signals even though; the saniesignals may be received satisfactorily by'ene or more oflthe otherreceivers;

Acccrdinglto the `present invention, these conditions which ofttimes prevent the reception of signals may be removedby incorporating into the receiving system suitable means for selecting that receiver which delivers the best signals and for excluding the outputs of all other receivers from thesystem. With such an arrangement all of the various receivers will always be available for monitoring purposes to receive signals from a ship transmitter withinlthe service area, but immediately after a cally is received fromsuch a ship transmitter, the receiver delivering the best output may be selected, if desired, or the outputs of two or more receiversmay be combined, if preferred, while `the remaining receivers are disconnected from the circuit. In that case signals of rgood quality may be received and the outputs of receivers which are not delivering good signal energy may be eliminated. After va call is completed, however, all of .the receivers are` returned to the monitoring condition automatically and l thus held available' for another call.

It is one .of `thevobjects of .thisy invention to employ a plurality of radio or other receivers to simultaneously Y, monitoroneaor more radio or livering the bestsignaloutput and transmit its signalslwhil'e disconnecting theremaining receivl ers fromthe circuit..`

receivers tothe circuit aitera callhasbe-en com-v pletedso thatallet the receivers will beavail-` able to reeeiveanother call. i i

Theiremairiing objects `and vvieaturesof this in-` vention.` may` be better `understood from `thedetailed"descripticn hereinafter following, when read in connection with the accompanying "drawing showingl two lembodiments `of `thisV invention merelyA for ythe purpose of illustration, `Figure 1 illustrating one forni of circuit arrangement for controlling the cutputsof two `or more radio receivers and Fig@ illustrating a modified arrange ment to accomplish thesame end.` v

Referring to Fig.v `1 of thewdrawing, ,a radio transmitter RT is associated with a plurality of The transmitter. and the `various receivers .may

radio Vreceivers RRifand R'Raonly two of :which `are shownmerely for the purposeof illustration.`

form .part ci a coastalharbor radio telephone system arn'n'igedV so that signals may be transmit#l ted by an? operator from a common point through. the `transmitter .RT and-signalsfreceived by; the variousreceivers RRi, RRz,l etc.

The-radio receiver Riti is connected to one of the input circuits of a hybrid coil networkHCi throughthe armatures and back contacts of a relay R1. radio-` receiver RR2 is connected toanother input circuit ofI the same hybrid: coil network HC1 through the `armatures andtback-contacts ofv a relay` Raf The fhybrid vcoil network` HC1 is of the typ-e described `inPatents Noa-1,780,962 and 1,780,963, issued November 11; 1930, toA. Bailey Siimilarly,V thefoutput circuit ofthe et al.k Suche hybrid coil networkmay be employed to combine `the outputs of the ftwo radio receivers Rlltlr and RRZ and the combinedenergy may beltransinittedv to a receiving orother circuit, as will be described more fully hereinafter. It

will be understood that the hybrid coil network referred to isbut one form of combining'circuit and that'othercornbining `circuits may be used" instead thereof. C l

The output ,circuit` of the hybrid coil network` HC1 is connected to the input circuit of a hybrid coil network HG2. The radio transmitter RT is connected to the output circuit of the same' hybrid coil network HC2. The tip and ring contacts of the jack J are connected to the third circuit of the hybrid coil network HC2. A telephone circuit (not shown) of well known `type is connected by means of a plug to the jack J so that telephone or other signals may be transmitted through the network HC2 to the transmitter RT for transmission through space, while signals received at either or both of the input circuits of the network HC2 may be received over the tip and ring contacts of the jack J by the operators circuit connected thereto. The hybrid coil network HC2 may be of any well known type, for example, of the familiar three-winding transformer type.

The sleeve contact of the jack J is connected to the winding of a relay R3 in such a way that current may be transmitted through the winding of this relay whenever the plug P is inserted into the jack J. The armature of this relay connects a battery B0 to the windings of two or more relaysdesignated R11, R12, etc., through corresponding resistors Z11 and Z12, respectively. The terminals of the winding of relay R11 are connected to the on and 01T contacts of a non-locking key K1, the armature of which is grounded. Similarly, the terminals of the winding of the relay R12 are connected to the on and off contacts of a non-locking key K2, the armature of which is also grounded. The upper armatures and back contacts of relays R11 and R12, respectively, control the circuits of lamps L11 and L12, current for illuminating lamp L11 being provided by battery B11 while battery B12 supplies the current to illuminate lamp L12. A single battery may replace batteries B11 and B121'f so desired. The relays Ri1and R12 are normally unoperated and, therefore, the lamps L11 and L12 are normally illuminated.

The upper make contact of relay R11 is connected to one terminal of the winding of relay R1, the other termnal of which is connected to a battery B1, as shown. Similarly, the upper make contact of the relay R12 is connected in circuit with the Winding of relay R2 and a battery B2. Both relays R1 and. R2 are normally unoperated so that both radio receivers RR1 and RR2 are connected to the respective input circuits of the hybrid coil network HC1. When the relay R1 s operated the radio receiver RR1 is disconnected from the corresponding input circuit of the network HC1 and an impedance Z1 is substituted therefor. Similarly, the operation of relay R2 will disconnect the radio receiver RR2 from the corresponding input circuit of the network HC1 and substitute the impedance Z2 therefor. The impedances Z1 and Z2 are showny in the form of resistors merely for the sake of simplicity but may be devices having induotance, capacitance and resistance which correspond to the vinduotance, capacitance and resistance components in the output circuits of the receivers RR1 and RR2, respectively,

When a signal is received by one or more of the various radio receivers RR1, RR2, etc., the operator may plug the cord circuit into the jack J 'to `receive the call. When this happens the relay R3 will operate to connect the battery Bo to the windings of relays R11 and R12in parallel through resistors Z11 and Z12, respectively. The outputs of the receivers RR1, RR2, etc.,` will be combined in the network HC1 and the combined energy 4will be transmitted through the network HG2 to the operators circuit which is plugged into the jack J.

If the operator desires to cut off the radio receiver RR1 he will move the armature of the key K1 to its off contact momentarily. The relay R11 will then be operated, current flowing from the battery B0 through the armature and contact of relay R3, resistor Z11, the winding of relay R11, the oli contact of armature of key K1, and ground. The operation of relay R11 will open the circuit of the lamp L11 at the upper back contact of this relay, at the same time connecting ground to the lower terminal of the winding of relay R11 for the purpose of locking up the relay R11. The closure of the upper make contact of relay R11 will cause the relay R1 to operate, current flowing from battery B1, through the winding of relay R1, and over the make contact and armature of relay R11 and ground. The operation orf relay R1 will disconnect the radio receiver RR1 from the circuit and replace that receiver with the impedance Z1. In that case the signals received by the radio receiver RR2 will be transmitted through the networks HC1 and HC2 to the exclusion of the signals that may be impressed upon the radio receiver RR1.

Similarly, by moving the armature of key K2 to its oil contact momentarily, the radio receiver RR2 may be disconnected from the hybrid coil network HC1 and the impedance Z2 substituted therefor. At the same time the lamp L12 will be extinguished by the opening of the circuit of the upper back contact of the relay R12 and the relay R12 will be locked upI by the closure of the lower make contact thereof.

If the operator desires to reconnect the radio receiver RR1 to the hybrid coil network HC1 he will merely throw the armature of the key K1 in reversed direction to its on contact momentarily. When this happens the upper terminal of the winding of relay R11 will be grounded through the on contact and armature of key K1. The relay R11 will, therefore, release. The lamp L11 will then become reilluminated by the closure of the circuit of the upper back contact of the relay. The relay R1 will become released upon the opening of the upper make contact of relay R11 and therefore the impedance Z1 will be disconnected from the hybrid coil network HC1 and the receiver RR1 substituted therefor. Similarly, by reversing the position of the armature of the vkey K2 and moving it to its on contact momentarily, the lamp L12 will become illuminated, the relay R12 released, the relay R2 released, the impedance Z2 disconnected from the corresponding input circuit of network HC1 and the radio receiver RR2 substituted for the imf pedance Z2.

The radio receivers RR1and RR2 are the only two receivers shown in the drawing but, as already explained, other receivers may be added to the system. If twofother receivers are employed they may be connected to a hybrid coil network similar to theone designated HC1 and the output of the additional hybrid coil network combined with that of the ouput of the network HC1 in still. another hybrid coil network which may be connected to the three-winding coil network I-IC2, as illustrated and explained inthe patents to A. Bailey et al., above designated. Of course, as many more radio `receivers may be connectedto the system as may be found desirable. I

The arrangement in Fig. 1' of the drawing permits the output.` of one of the `radio receivers such as RRito be transmitted through the hybrid coil networksHC1 and IIC2` to the operators set to the exclusion of the' outputs of all other radio receivers. It .will be understood, also, that the output of. the radio receiver RR2 may be thusl selectively transmitted to the operators setto the exclusion ofthe outputs of the other radio receivers. Similarly, if three or more radio receivers are employed,the outputs of any two or more of` these various receivers may be combined and vtransmitted through. :the .hybrid coil net- 1 Work HG2 to the operators set while the outputs of the remaining receivers are suppressed or elim-` inated from they operators circuit. When a callV has `been completed the operators plug P will be removed from the jack J and all of the var- Y ious radio receivers will be returned to their monitoring condition to receive signals simul- Cil.

taneously from any radio transmitter within the 1 service area.

the receivers RR1 and RR2.

When the operatorsplug P is inserted in the jack J, relay R3 operates so that battery B11 may be connected through the armature and contact of the relay R4 to the windings of relays R11 and R12 (and to other relays which may be connected to the circuit) through the corresponding resistors Z11 and E12, respectively., vThe key K11 controls `the operation of the relay R2. Keys K11"V and K12 control the operation of relays R21 and R22, respectively, the latter relays being associated with the corresponding relays R11 and R12. As the relays R11 and R12, are normally unoperated, the

lamps L11 and L12 are normally illuminated, as

already described with respect to Fig. l.

Before the operators plug P plug P is inserted into the jack J and relay 'R3 is operated, the relays R11 and R12 may only then be operated, and this will be described more fully hereinafter. y

While the operators plug is inserted into the jack J the key K11 may be closed rmomentarily. The relay R21 will then operate, current flowing from battery B21 through thewinding of relay R21 over the contacts of key K11 andground.`

The operation of relay R21 opens the circuit of relay R11`at the back contact of relay R21, thereby preventing the operation of relay R11. The release of relay R11 will cause the lamp L11 to be illuminated or to 'remain illuminated if pre-l viously in this condition. At the same time the armature of relay R21 becomes grounded at its make contact and causes the operation of relay R12, current for the relay R12 being provided by the battery Bo connected to the contact of relay R3 thev current flowing over the armature;

and contact of relay R1 through resistor Z12, over the winding of relay R12, the armature rand back contact of relay R12, the armature and 'back` contact of relay R22, the armature and make contact of relayv R11 and ground.` Hence relay R12 will operate and its operation will cause the relay 1 R2 to operate, which in turn will disconnect the r'c'eiver RR2 from the input circuit of the hybrid coil network HC1 and replace the receiver RR2- g receivers except the radio receiver RR2.

is` inserted into the jack J, relay R3 is unoperated and therefore the relays R11 and R12 will be unoperated and l -will remain unoperated. But after the operators` withzthe impedance Z2'.`

Thus thev operationfof key K11 wille-remove `the radiofreceiver RR2`from the `circuit as well as all other receivers except .the`

radio-receiver RR1.

The operation of key K12 will cause the opera.` tion .of relay R22, current owing from-battery B22, through the winding of relay R22, over :the contacts of keyK12 and ground. The operationof` relay R22ywill open the circuit of relay R12 at the back contact of relay lR22 so that relay R12 will remain unoperated. Thelamp L12 will therefore be illuminated." The release of relay R12 -willV cause the receiver RR2 tobe` connected `to vthe input circuit of the 'network HC1. The operation of relayR22 will placegroundon the maket contactothe relay and cause relay R11 to oper- 1 ate. The current forsrelay R11 is supplied by battery `Bathr'ough the contact and armature of relay R2, over the armature and contact of` relay R4, .resistor Z11, the winding of relay R11, the armature and back contact of relay R11, the armature' .and back contact of relay R21, the

Y armatureyand make contact of relay R22 andr ground. The closure of the make contact of' relayR1l will connect ground tothe lower ter.-

rninal of the winding `of this relay and lock up the relay.` The operation of relay R11 will ,cause the operation ofrelay R1, as in thecase of Fig. `l,

and `disconnect the radio receiver RR1 from the hybrid coil network HCl andsubstitute theini-` pedance'Z1` for the radio receiver RR1. `Thus the operationv of key K12 will disconnect the, receiver RR1 from the circuit as well as all other It hasthus been' shown that the closure of key K11 causes the operation of relays R21 and R12 and allows the relayR11 to remain'unoperated, this condition being indicated by the illumina` tion orlamp L11. It. has also been shown thatv A'the operation of key K12 lcauses the operationfof vrelay R22.Y and relayRn, causing the relay R12 to remain unoperated, this condition ,beingindicated by the illumination of lamp L12. 1

Ifthe operators plug P should remain locked in theijackJ and if it is desired to have allot' theradio receivers connected to the operators set, it is only necessary to operate the key '-Ku.

The operation of key K0 will cause the operation of relay R4, current flowing from battery B1 through the winding of relay R4 over the con. tactsloffkey Kn and, ground.` Theoperation of relay R4 4will disconnect the battery B4 connected over the contact and armature of relay B3 from v the windings of relays R11, R12, etc. The relays R11 and .R12 will therefore be unable to operate and therefore the receivers RR1 and RR2 will be connected to the hybrid coil network HC1. After the operatorsplug P has been removed `from the jack J, relay R3 is released and the operation of key Ko will, of course, serve no useful `purpose because no current may then be supplied to the windings of relays R11 and R12. n

i rIv'he circuit arrangements illustrated in Figs. 1 and 2 of the drawing `have been applied to the selection of the radio receiving circuits whereby oneof the radio receivers will be selected and connected to the circuit and all other radio receivers `disconnected from the circuit. It will be clear, of course, that thearrangements may be employed-for the selection of devices other than radio receivers, for example, detectors or other devices or circuits.

f `While this invention has been 'shown and describedin certain particulararrangements merely for the purpose of illustration, it will be undersiod' that' the gener'a'i principes of this in: vention may be applied to other and widely varied organizations without departing from the spirit l 'of the invention and the scope of the appended for observingits output and for disconnecting all of the other receivers'from the receiving circuit, means "for indicating which of the various recevers has ybeen selected by the selecting means,

. and means for subsequently reconnecting all of said radio receivers to the common receiving circuit so that the outputs of all of said receivers may again be received by said common circuit.

2. The combination of a plurality of radio receivers all adapted to receive and monitor the same signals, an operators set with which all of the radio receivers may be connected for simultaneously receiving the outputs of all of said recevers, means for selecting the receiver delivering the best .output and forv connecting the selected receiver to the operators set, said means also including means for simultaneously disconnectingall of the remaining radio receivers from the operators set, and means for subsequently reconnecting all of said radio receivers to the Aoperators set.

" '3., The combination of a plurality of radio rey ceiving circuits all of which are simultaneously monitoring a distant station, an operators set to which all of the receivers may be simultaneously connected so that the outputs of all of said receivers `may be simultaneously received, means for selecting the radio receiver delivering the best signalsand for disconnecting all other radio re-v ceivers from the operators set, and a plurality of indicating devices each corresponding to one of the radio receivers for indicating which one of the various receivers is connected to the operators set.

4. The combination of a plurality of radio receivers all of which may, be tuned to simultaneously receive signals from a distant station, a

telephone circuit to which all of the radio'recevers may be connected sdthat the' outputs 'of all of said receivers may be simultaneously received, means forcombining the outputs of certain .of said receiversfor transmission to said telephone circuit' and vfor disconnecting all of the remaining receivers :from -thetelephone circuit, and indicatingmeans for indicating which of the various radio receivers are connected to the telephone circuit.

5. In a signaling system, the combination of a plurality of receiving circuits all employed `for simultaneously monitoring adistant mobile staf tion, a telephone circuit, a combining network interconnecting all of the receiving circuits with the telephone circuit so that .the outputs of all of the receiving circuits maybe translated into audible'signals, means for disconnecting from the combining network certain of said receiving circuits so` that the outputs of the remaining receiving circuits will be additively combined in the `combining network, and means for subsequently reconnecting all of the receiving circuits to the combining network for further monitoring the distant mobile station.

6. The combination of a plurality of receiving circuits, a plurality of impedance elements, each impedance element corresponding to one of the receiving circuits, a combining network, means `for connecting all of the receiving circuits to the combining network, means for disconnecting all of the receiving circuits from the combining network except one and orreplacing each disconnected receiving circuit with the corresponding impedance element, and means for subsequently disconnecting all of the various impedance elements and for reconnecting all of the various receiving circuits to the combining network.

7. In a signaling system, the combination of a plurality of interconnected radio receivers for simultaneously monitoring one or more mobile stations that may be transmitting signals, means for selecting that one of said receivers delivering the best output and observing its output and for disconnecting all other of said receivers from the interconnecting circuit, means for transmitting signals to the mobile station from which signals sof' are being received, and means for subsequently 

